Introduction: Bacterial meningitis is a rare (about 1,200 cases per year in France, 50% occurring in adults) and serious disease (20% mortality during the acute phase; neurosensory sequelae in 30% of survivors). Major changes in the epidemiological characteristics of bacterial meningitis have been observed as a result of changes in behaviour, human interventions (use of antibiotics, prophylactic vaccinations), as well as poorly elucidated mechanisms responsible for epidemic outbreaks. No standardized clinical, microbiological and prognostic data collection concerning bacterial meningitis in adults is available in France.